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/*! \file
    \brief Templates implementing computing the addresses of storing of small
   scale and bias vectors in the shared memory.
*/

#pragma once

#include "cutlass/cutlass.h"
#include "cutlass/array.h"
#include "cutlass/layout/pitch_linear.h"
#include "cutlass/layout/matrix.h"
#include "cutlass/matrix_coord.h"
#include "cutlass/matrix_shape.h"
#include "cutlass/tensor_ref.h"

////////////////////////////////////////////////////////////////////////////////

namespace cutlass {
namespace conv {
namespace threadblock {

////////////////////////////////////////////////////////////////////////////////

/// RegularScaleBiasVectorAccessIterator
///
template <typename Shape, typename Element, typename Layout>
class RegularScaleBiasVectorAccessIterator;

////////////////////////////////////////////////////////////////////////////////

/// Tile iterator specialized for congruous arrangements for TensorOps
///
///
/// Satisfies: ForwardTileIteratorConcept |
///            ReadableContiguousTileIteratorConcept |
///            WriteableContiguousTileIteratorConcept
///
template <typename Shape_, typename Element_>
class RegularScaleBiasVectorAccessIterator<Shape_, Element_,
                                           layout::PitchLinear> {
public:
    using Shape = Shape_;
    using Element = Element_;
    using Layout = layout::PitchLinear;

    using Index = typename Layout::Index;
    using LongIndex = typename Layout::LongIndex;

    using TensorRef = TensorRef<Element, Layout>;
    using TensorCoord = typename Layout::TensorCoord;

    /// Element type per access
    static int const kElementsPerAccess = 128 / sizeof_bits<Element>::value;
    static int const kThreads = Shape::kContiguous / kElementsPerAccess;
    using AccessType = Array<Element, kElementsPerAccess>;

private:
    //
    // Data members
    //

    /// Internal pointer
    AccessType* pointer_;

    /// Internal byte offset
    Index byte_offset_;

public:
    /// Construct a TileIterator with zero threadblock offset
    CUTLASS_HOST_DEVICE
    RegularScaleBiasVectorAccessIterator(
            TensorRef scale_bias_ref,  ///< Pointer to the start of the scale
                                       ///< and bias vector
            int thread_id  ///< ID of each participating thread
            )
            : byte_offset_(0) {
        // Per-thread offset in logical coordinates of tensor
        int thread_offset = thread_id * kElementsPerAccess;

        // initialize pointer
        pointer_ = reinterpret_cast<AccessType*>(scale_bias_ref.data() +
                                                 thread_offset);

        set_iteration_index(0);
    }

    /// Overrides the internal iteration index
    CUTLASS_HOST_DEVICE
    void set_iteration_index(int index) {}

    /// Adds a pointer offset in units of Element
    CUTLASS_HOST_DEVICE
    void add_pointer_offset(LongIndex pointer_offset) {
        byte_offset_ += pointer_offset * sizeof(Element);
    }

    /// Returns a pointer
    CUTLASS_DEVICE
    AccessType* get() const {
        char* access_byte_ptr = reinterpret_cast<char*>(pointer_);

        return reinterpret_cast<AccessType*>(access_byte_ptr + byte_offset_);
    }

    /// Advances to the next tile in memory.
    CUTLASS_HOST_DEVICE
    RegularScaleBiasVectorAccessIterator& operator++() { return *this; }

    /// Advances to the next tile in memory.
    CUTLASS_HOST_DEVICE
    RegularScaleBiasVectorAccessIterator operator++(int) {
        RegularScaleBiasVectorAccessIterator prev(*this);
        this->operator++();

        return prev;
    }

    /// Adds a tile offset in the unit of tile.
    CUTLASS_DEVICE
    void add_tile_offset(TensorCoord const& coord) {
        // Multiply by 2 because we store sclae and bias belong to the same
        // stage next to each other.
        add_pointer_offset(coord.contiguous() * Shape::kContiguous * 2);
    }
};

////////////////////////////////////////////////////////////////////////////////

/// Tile iterator specialized for row major layouts
///
///
/// Satisfies: ForwardTileIteratorConcept |
///            ReadableContiguousTileIteratorConcept |
///            WriteableContiguousTileIteratorConcept
///
template <typename Shape_, typename Element_>
class RegularScaleBiasVectorAccessIterator<Shape_, Element_, layout::RowMajor> {
public:
    using Shape = Shape_;
    using Element = Element_;
    using Layout = layout::RowMajor;

    using Index = typename Layout::Index;
    using LongIndex = typename Layout::LongIndex;

    using TensorRef = TensorRef<Element, Layout>;
    using TensorCoord = typename Layout::TensorCoord;

    /// Underlying iterator type
    using UnderlyingIterator = RegularScaleBiasVectorAccessIterator<
            layout::PitchLinearShape<Shape::kColumn, Shape::kRow>, Element,
            layout::PitchLinear>;

    using AccessType = typename UnderlyingIterator::AccessType;

private:
    /// Underlying iterator
    UnderlyingIterator iterator_;

public:
    /// Construct a TileIterator with zero threadblock offset
    CUTLASS_HOST_DEVICE
    RegularScaleBiasVectorAccessIterator(
            TensorRef scale_bias_ref,  ///< Pointer to the start of the scale
                                       ///< and bias vector
            int thread_id  ///< ID of each participating thread
            )
            : iterator_({scale_bias_ref.data(), scale_bias_ref.stride()},
                        thread_id) {}

    /// Overrides the internal iteration index
    CUTLASS_HOST_DEVICE
    void set_iteration_index(int index) {
        iterator_.set_iteration_index(index);
    }

    /// Adds a pointer offset in units of Element
    CUTLASS_HOST_DEVICE
    void add_pointer_offset(LongIndex pointer_offset) {
        iterator_.add_pointer_offset(pointer_offset);
    }

    /// Returns a pointer
    CUTLASS_HOST_DEVICE
    AccessType* get() const {
        return reinterpret_cast<AccessType*>(iterator_.get());
    }

    /// Adds a tile offset
    CUTLASS_DEVICE
    void add_tile_offset(TensorCoord const& coord) {
        iterator_.add_tile_offset({coord.column(), coord.row()});
    }

    /// Advances to the next tile in memory.
    CUTLASS_HOST_DEVICE
    RegularScaleBiasVectorAccessIterator& operator++() {
        ++iterator_;
        return *this;
    }

    /// Advances to the next tile in memory.
    CUTLASS_HOST_DEVICE
    RegularScaleBiasVectorAccessIterator operator++(int) {
        RegularScaleBiasVectorAccessIterator prev(*this);
        ++iterator_;

        return prev;
    }
};

////////////////////////////////////////////////////////////////////////////////

}  // namespace threadblock
}  // namespace conv
}  // namespace cutlass

////////////////////////////////////////////////////////////////////////////////
